Supplementation with Sources of Fiber or Starch for Finishing Steers Grazing Winter Pastures

Abstract

This study assessed the effect of supplementation with concentrate or roughage on the performance of steers grazing on rye grass previous to slaughter. The experiment was conducted on two consecutive years (Y) on 23 ha of Lolium multiflorum LE 284. Forty-eight Hereford steers (year 1) and 36 (year 2), were randomly allotted to 12 groups and one of four treatments (T): grazing without supplementation (GR); grazing plus grass hay (Setaria itálica) restricted (HR) or ad libitum (HAD); and supplementation with ground sorghum grain (SG, 1 % live weight, LW). Data were analyzed according to a completely randomized design with factorial arrangement of treatments. Available forage biomass was higher in year 2 (1932 vs. 2806 kg/ha, P < 0.01), with no differences due to T (P > 0.05), or to the interaction Y × T (P > 0.05). Interaction Y×T did not affect any of the performance or carcass variables (P > 0.05). SG increased daily intake, live weight gain (LWG), LW at slaughter, carcass weight and carcass fat compared to GR (P < 0.05). Conversely, neither HR nor HAD improved cattle performance at slaughter compared to GR (P > 0.05). These results do not sustain the hypothesis that supplying restricted amounts of grass hay would improve the utilization of ingested pasture.